Why do ionic solids have high melting points, and high boiling points?
Consider the inter particle force that operates in ionic solids.
Ionic solids are non-molecular. Each cationic particle is electrostatically bound to every anion in the solid. Of course there is electrostatic repulsion between like charges, but if you sum up attractive versus repulsive forces across the structure (and chemists can do this) a net attractive force results. This attractive force is hard to disrupt, and accounts for the high melting and boiling points of most ionic solids.
Contrast these properties with those of molecular solids. Here there are discrete molecules, and, typically, intermolecular force is indifferent. As a chemist, as a physical scientist, you should look up some representative physical properties.